The present invention relates to the field of photography and, more specifically, to processing apparatus for applying a processing sheet or web, carrying a substantially uniformly distributed supply of processing liquid thereon, to an exposed sheet-like film unit to wet an outer surface of the film unit and thereby initiate film processing.
It is well known in the prior art to process film units with a processing sheet that is soaked with processing liquid or includes a liquid carrying gel layer.
For example, the processing sheet may comprise a support carrying on one surface thereof a gel consisting of a polymer solid phase and a liquid phase comprising an aqueous alkaline processing composition. Processing is accomplished by laminating the processing sheet to the film unit with the gel in contact with an outer surface of the film whereupon the aqueous alkaline processing composition diffuses into the film and develops the exposed silver halide.
This type of processing sheet may be configured to process a variety of photosensitive materials including black and white and color self-developing diffusion transfer film units which include in a multilayer structure one or more photosensitive layers and an imaging receiving layer.
The processing sheet may be adapted to be removed from the film after an appropriate processing interval or it may be designed to be left in place permanently to act as protective cover sheet. The processing sheet support may be opaque to protect the photosensitive layer(s) from additional exposure during processing and may be left in place if applied at a non image viewing surface of the film or removed later if the film is of the type wherein the gel is to contact the image viewing surface. Alternatively, the processing sheet support may be transparent for use with film units wherein the gel is to contact the image viewing side of the film and the processing sheet is left in place to act as a transparent cover sheet.
For representative examples of processing sheet structures that employ an absorbant web soaked with a low viscosity processing liquid or utilize a processing gel carried or a support or formed as a self-supporting layer, reference may be had to U.S. Pat. Nos. 2,558,857; 3,229,605; 3,282,695; 3,615,482; 3,680,462; 3,826,653; 3,907,563; 3,930,859; and 4,443,530.
In certain applications, it may be desirable also to laminate a backing or support sheet to the underside of the film unit to provide additional stiffness and durability to the finished photograph. Furthermore, the backing sheet may be larger than film and be of an appropriate color (e.g., white) so that the marginal portions that extend beyond the edges of the film unit provide an attractive border around the finished print. For example, see U.S. Pat. No. 3,949,501 wherein an ID photograph is laminated between a transparent (non-processing) cover sheet and a border providing cover sheet. In such applications, it would be highly desirable, from an efficiency and cost standpoint, to simultaneously laminate the processing and backing sheets to opposite sides of the exposed film unit. For an example of an apparatus that includes a section for simultaneously laminating cover and backing sheets to opposite sides of an ID card, see U.S. Pat. No. 3,158,523.
One major advantage of the processing sheet method is that the processing liquid is uniformly predistributed and does not have to be mechanically spread as in the case of conventional self-developing film units wherein the liquid is held in a rupturable pod at one end of the image forming area. This means that processing apparatus for use with a processing sheet only needs a relatively inexpensive pair of pressure rollers to urge the sheet and film into good contact rather than very expensive precise rollers, used with the more conventional pod type film unit, that function to rupture the pod and then spread the liquid uniformly between predetermined layers of the film unit.
There is, of course, a drawback to the processing sheet or web method in that chemically active processing liquids, such as aqueous alkaline developers, must be protected from prolonged atmospheric contact before use. If the processing sheet is exposed to air for a long period of time, some of the liquid may be lost by evaporation and/or the liquid may be contaminated or suffer diminished chemical activity because of its reaction with atmospheric gases such as oxygen and carbon dioxide.
The liquid carrying processing medium may be produced in single sheet units dimensioned to cover a single film unit or in the form on an elongated web roll used for high volume production wherein a predetermined length of the processing wet is cut from the roll just prior to or after lamination. The processing sheets or rolls generally are packaged in vapor and gas impervious containers or bags at manufacture which provides protection against atmospheric contact until the sheet or web is to be used. An individually packaged sheet presents no problem in that it is used immediately upon being removed from its protective packaging. However, an elongated processing web roll is used intermittently, a length at a time, and some protection against prolonged atmospheric contact must be provided for the unused portion of the roll once the protective package is removed or opened.
Commonly assigned U.S. Pat. Nos. 3,229,605; 3,254,583; 3,314,791; 3,314,792; and 3,345,165 disclose various embodiments of a self-developing camera and a compatible cassette holding a roll of processing web that is soaked with a low viscosity processing liquid. The camera and/or cassette include structure for isolating that portion of the roll left in the cassette from the ambient atmosphere when the camera is in its non-processing mode.
The cassette comprises a vapor and gas impervious housing formed around the processing web roll. The housing has a single exit opening or slot through which the web is advanced in increments to present an appropriate length of web at a pair of pressure rollers which are used to laminate the web to a length of exposed film. A knife assembly on the exit side of the rollers is provided for severing the laminate from the trailing processing web and film strip.
The cassette exit opening is sealed at the factory so the web is protected until the seal is broken just before the cassette is inserted into the camera. In one embodiment, the edges of the exit opening are resilient and overlap to clamp the protruding web between integrally formed ribs to inhibit vapor and gases transmission through the exit open. Thus the cassette itself includes means for isolating the processing web or sheet from the ambient atmosphere. In another embodiment, the cassette is provided with a pair of compliant outwardly extending lips on opposite sides of the exit open and the camera includes means for selectively applying a compressive pressure to the lips to clamp the protruding portion of the web therebetween and thus ilsolate the portion of the roll inside the cassette from the ambient atmosphere.
In this system, the processing web is advanced along one path of travel into the nip of the pressure rolls while the film unit is advanced along a path that is substantially perpendicular to the web path. This means that the convergent paths must be set to fairly precise tolerances if the film and web are to be in proper registration alignment when they enter the bite of the rollers. Such tight tolerance requirement, of course, increase the cost of the processing components. Also, no provision is made for simultaneously laminating a backing sheet to the underside of the film unit.
Therefore it is an object of the present inventor to provide a low cost and easy to use film processing apparatus having processing and non-processing modes of operation, and including means for isolating a processing sheet or web carrying a substantially uniformly distributed supply of processing liquid from the ambient atmosphere surrounding the apparatus when the apparatus is in its non-processing mode.
Another object is to provide such an apparatus that is configured for use with a processing sheet cassette having both entry and exit openings.
Yet another object is to provide such an apparatus that includes provision for simultaneously applying a processing sheet and a backing sheet to opposite sides of an exposed film unit.
Another object is to provide a low cost and easy to use film processing system comprising a film processing apparatus in combination with a cassette holding a processing sheet.
Yet another object is to provide such a system wherein the cassette includes means for properly aligning film unit with respect to the processing sheet.
Still another object is to provide a cassette holding both a processing sheet and a back sheet, which is configured for use with a film processing apparatus.
Other objects of the invention will, in part, be obvious and will, in part, appear hereinafter.